Molecular size of proteins is assessed by

Mass spectrometry (MS) is a very sensitive quantitative analytixal technique used to measure a wide range of clinically relevant analysis.MS identifies molecules based on their mass or molecular size. A sample is vapourized sucj that positive charge is produced on the molecule.Electrical field is applied, so that paiclss move.At the same time , a magnetic field is applied , so the cations are deflected at the right angle to their original direction , and hit on the detector For molecules of identical charge ,the time required for the inversely propoional to the mass of the molecule.Conventional MS identifies molecules of 4000 D or less.For higher moleculer size materials, time-of-flight mass spectrometers are useful Reference:DM VASUDEVAN Text book SEVENTH EDITION pageno : 39 and 458